Quantitative thermography: a powerful but simple tool to assess the fatigue strength of metals in a one-specimen test–capabilities and limitations in the test setup
International Journal of Structural Integrity
ISSN: 1757-9864
Article publication date: 14 November 2022
Issue publication date: 8 February 2023
Abstract
Purpose
The aim of the study is the question, that is, which evaluation method for the measured temperature profile is more suitable and feasible for quantitative thermometry (QT): A simple measurement setup based on 3-point temperature sensing by means of semiconductor sensors (NTCs) or thermographic methods which offer 2-dimensional (2D) temperature measurements of the sample with good spatial resolution but an inferior temperature sensitivity. What experimental effort is required to adjust the test setup to satisfy the boundary conditions of the underlying thermodynamic equations?
Design/methodology/approach
In this paper results of both methods are contrasted and the error of QT measurement is assessed by finite element analysis (FEA) in this follow-up.
Findings
The low-cost NTC method allows a straightforward determination of a lower estimate of the fatigue strength with only a very small measurement error. Even asymmetries in the thermal boundary conditions of the test setup are broadly tolerated, as well as a lack of thermal isolation.
Practical implications
The method is restricted to metallic materials without phase transitions during fatigue in the fatigue strength regime.
Originality/value
QT is not a new method. The assessment of the methods proposed in the literature regarding their practicability in terms of accuracy is innovative focus of this work. Nevertheless, highly accurate thermometric measurements can be performed by using simple commercial sensors in combination with a standard digital multimeter.
Keywords
Acknowledgements
The authors thank Dr. Michael Roland from Applied Mechanics at Saarland University for the fruitful discussion about fitting tools in MATLAB. The authors thank Dres.-Ing. Peter Starke and Hoaron Wu from Hochschule Kaiserslautern for their support during data acquisition with the IR camera.
Funding: No funding was received.
Competing interests: There are no competing interests.
Citation
Rauber, J., Motz, C. and Schaefer, F. (2023), "Quantitative thermography: a powerful but simple tool to assess the fatigue strength of metals in a one-specimen test–capabilities and limitations in the test setup", International Journal of Structural Integrity, Vol. 14 No. 1, pp. 91-102. https://doi.org/10.1108/IJSI-05-2022-0074
Publisher
:Emerald Publishing Limited
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